15 inch wheels for 90 CRX

[REPPHD]

I am running 14X7 with 225 Kumho's. Anyone tried successfully to put 15 inch tires on the car? My crew suspects there is not a chance in fitting. Any thoughts or suggestions.

[darthmonkeyIT]

I believe I have heard of it being done. 225's in Kumho's are skinnier than 225 Hoosiers and I have heard (HEARD mind you) that if you flare the fender wells a bit and accept that you can not turn near wheel lock you can get 225 R15 Hoosiers on. A 205 Hoosier is about the width of a 225 Kumho. Same goes for the Hankook Z214's at 225 compared to a Hoosier 205.

There might be some rub though on the rear trailing arms which is why I have also heard in order to be able to run 225 R15's you need a large spring rate in the rear (heard 1000#'s). This is to prevent the car from leaning over the tire and instead lean the tire over with the lean of the car. It is also nick-named knife edge driving at that spring rate because the car will tend to hook around corners but if you get it wrong you end up pointed the wrong way.

[raffaelli]

Hoosier 15 225 will fit. A fast crx in the northeast runs them. Not sure what the offset is. He does not run 1000 in the rear.

What performance gain are you looking for over the tire 14 225?

[Chip42]

as above, you might need some spacer or rolling the fender, but 15" hoosiers are actually very very close to the same rolling diameter as their 14s (less that 0.1" difference 225-225 and 205-205) so if you can fit a 225 R14, and MANY have, you can fit the 15s as well. 15" stock wheels from the integra work (basket weave and daisies) and Phil's Tire Service and TrackSpeed Motorsports sell a 15x6 DForce wheel called the CR6 which will fit your car, too.

[REPPHD]

thanks guys.

I run 225 50 R 14 at 22.8 OD, 9 inch width KUMHO which are a bit wider than Hoosier

225 50 R15 would be 23.7 OD sames width.

At RA I run the 4.73 gears. Now I know I could go back to 4.11 which would change the rev pattern and that is an option for next year.

I ran 2.50 on Saturday, did not try and go fast on Sunday as it was my last race this season anyway and I was not running enough to challenge anyone in points. I think i could have run about 2:49 or a bit better with what I have. I run 650's in the back springs and my motor is good, but has no piggyback just a 6 year old chip at this point. In going through the carousel and Kink I would like to up my speed there and I have been pretty conservative there so I know I have time to make. My thinking with more OD, I would have less revs so be in a better power band to go into Canada and also pick up some advantages. Right now I do about 7000 into 1, 7000 into 5, but best into 12 was about 6700 on Saturday and maybe 6300 on Sunday.

So I think what you are telling me is it possible; we fixed the rub on the Kumho 14's early on; The 15 inch wheels I think are good at about 11 lbs are 35mm offset (miata). Bigger tires weigh more, but wheels keep total unspring weight gain to a minimum.

If I want to run with Midwest Council in the top three I have to be 2:48 and we did see 2:47 and even faster this year with a couple of national miata guys.

Further thoughts?

[Chip42]

225 50 R15 would be 23.7 OD sames width.
225 45 R15 hoosier is 22.9" diam.


At RA I run the 4.73 gears. Now I know I could go back to 4.11 which would change the rev pattern and that is an option for next year. taller tire is like going to a smaller gear. doing both would be murder unless you stepped down the gearbox and even then it rarely works out well as the spacing tends to increase in the bottom of the box. what you are talking about is a ~10-15mph change in 4th gear speeds at 7k RPM, and less acceleration on the way there.


So I think what you are telling me is it possible; we fixed the rub on the Kumho 14's early on; The 15 inch wheels I think are good at about 11 lbs are 35mm offset (miata). Bigger tires weigh more, but wheels keep total unspring weight gain to a minimum.
just be careful, Miata wheels are 54mm center bore, honda is 56. also, most of the Miata wheels I've seen are +45mm offset. spacers can take care of both problems though.

[Xian]

As others have said... yeah, 225/45 15 will fit. It's super duper tight in the rear (especially) but it'll work. Unless you've got a stockpile of 15x7's I wouldn't bother with it myself. Run the 225/50 14. Their slightly taller sidewall isn't bad thing in a SWB car like the CRX...

There's no way that I'd move an ITA CRX onto 225/50's. The taller tire height will raise the car, create clearance problems, hurt gearing, etc. No way, no day.

[adamjabaay]

I've been toying with the idea of running spec miata 205's 15'' tires on my crx

don't know if it'll happen. Lazy

[Davegt74]

(Keep in mind I am running solo II since I am trying to sell the Honda)

I switched to 225/45ZR15 Hankook s with RPF1's and I went and bought a fender roller

turns out my car's fenders where already rolled for the larger wheel and tire combo, I do have some slight rubbing in the rear and the front right I am finding grease on the front outer cv boot (I have wiped it off twice and can’t find any holes)

Here are the reasons I would not go with 15's (what I told myself in the past)

1) Doing so raises the ride height of the car (it’s normally anathema to raise the CG height of a car)


2) The tires and wheels are more expensive


3) Changes the final ratio

BUT I knocked off 2 seconds when I did it so that killed my arguments against doing it.

For this Sunday I am going up on the front spring rate 50 pounds to 500lbs

Davegt74

[Xian]

Assuming you're referring to the typical ITA wheel sizes...

1- 225/45 15's are essentially the same height as the more common 225/50 14. No ride height change results... and even if it did, you've got coilovers to adjust ride height.

2- Wheels and tires are cheaper on the used market due to increased commonality with other cars.

3- FD stays the same b/c of #1.

If you're comparing to the 225/50 the OP asked about, all of the common 15" sizes will lower the car and improve the effective FD. If you're comparing to something like a 225/50 13 then yeah... 15's would change things pretty drastically.

[madrabbit15]

We run 15 x7s with 205/50/15 hoosiers and kumhos. Works great, no problems what so ever. I personally don't see how any of the guys running 225s can do it. We have tried numerous ways and we either rub the rear trailing arm or the track is wider than the fender. Personally I think the 205s are faster than the 225s anyway. Takes too much hp for those wider tires on the faster straights.

[Xian]

We run 15 x7s with 205/50/15 hoosiers and kumhos. Works great, no problems what so ever. I personally don't see how any of the guys running 225s can do it. We have tried numerous ways and we either rub the rear trailing arm or the track is wider than the fender. Personally I think the 205s are faster than the 225s anyway. Takes too much hp for those wider tires on the faster straights.

I dunno... I'd say most ITA CRX's I've seen through the years ran 225/50 14's. I ran (IIRC) 14x7 38mm offset TD Pro Race 1.2's all the way around. There was a very small (2mm?) spacer used at the rears to keep them off the RTA too much. They'd still polish the RTA some but nothing worth worrying about. They'd clear the rolled rear fenders without any problems...

[adamjabaay]

my ita car runs 225 14'' on pnasports...38 offset I believe.

barely fits. But it fits great on decently rolled fenders all around. Same wheels all around


so yeah, what xian said

[Knestis]

To complicate the conversation, we ended up (through actual testing) running 225s on the front of Pablo the Golf and 205s on the rear. Hoosiers, all 14", and same height by different aspect ratio.

K

[ITA_honda]

Ive always run 205/50/15 with the Hoosier SM6 compound tires and the Enkei RPF1 wheels. Have had much success with them!

[Xian]

To complicate the conversation, we ended up (through actual testing) running 225s on the front of Pablo the Golf and 205s on the rear. Hoosiers, all 14", and same height by different aspect ratio.

K

Yup. And then you can complicate it even further by running the A compound at the rear...

[Chip42]

We've done some games with Steves MR2 showing ~2mph in a straight line at Roebling 205 R6 vs 225 R6. 225's were on 14" wheels, 205s were on stoopid light SSR 15", so not sure all of that is the tire. overall lap times were similar, but the speed was made differently. we also tried some mixed wide rear/narrow fronts but it unbalances the car toward understeer. was slightly faster in a straight line though.

explain the A comp on the rear thing... more grip on the rear = good why? or is there a weight issue or something else I'm missing?

[Xian]

explain the A comp on the rear thing... more grip on the rear = good why? or is there a weight issue or something else I'm missing?

Nah, it's not really a "more grip" thing more a matter of how quickly the rear end comes up to "normal" grip levels. On R's, a "fast" CRX is a handful for the first couple laps as the fronts gain heat/grip more quickly than the rears. Put R's up front and A's in back and they should come up to temp/grip more or less equally which lets you gain time in the first couple laps. Total grip potential at operating temp is (effectively) the same for the rest of the race and the rears never get so overloaded that they can go off or get greasy.

Disclaimer: this ^^^ is second hand info from folks who've gone down the road of staggered compounds. As much as I liked the theory of it, I preferred the ability to easily rotate tires front/back and even out wear and heat cycles.

[R2 Racing]

On my FP Integra, I run a harder compound on the front of my car than I do on the rear, because of what Christian is describing. If I try to run the softer compound all the way around, the fronts don't handle the heat and abuse over a long run, and it starts to push. If I run the harder compound all the way around, then the rears take too long to come up into their operating temp range, and I'm too slow at the start of the race. If I try to change the setup of the car so its more manageable on those cool rears at the start, then it tightens up to much for the second half of the race. But with the hards on the front and softs on the rear, they all come up to temp pretty evenly, and I can set up the car so its kick-ass, stuck like glue, and consistent over long runs.

On my ITA Integra though, I can't do a R6 front and A6 rear setup, as the rear-end grip becomes too much. That car just weighs too much (300lbs heavier than the FP car), and the IT rules restrict some other things that I can do on the FP car, that I end up having to rely on lack of grip in the rear-end to help it turn. I've ran A6's all the way around on many occasions, but it only works when it's cool out and I'm on a track that doesn't abuse tire, otherwise it cooks the fronts. Also done A6's front and R6's rear, again trying to make the rear-end NOT grip, and that's ok at a place like Mid-Ohio, but its still an exercise in not burning the fronts off. One thing I never tried though was a 225 R6 front and 205 R6 rear setup, which might have been decent.

[Davegt74]

I ran into something similar, during the course of a solo II event the car would oversteer more as the event went on (which also explained the problems I had on the road course at HPR in CO)

anyway I had to drop the spring rate in the rear 50 lbs. then I switched to the soft compound Hankook's with the 225/45/15 well that took care of the front wheel spin (at least while they were fresh)

Now based on front shot pictures it looks like the car is rolling 3 degrees so I am going to go up on the spring rates on the front which might lead to me going back up on the rear spring rates

Another thing I am learning (which is speculation on my part) is one of the reasons that fast drivers are fast is how they handle the rear of the car

Let me explain, it is often said a loose car is quicker/faster but its really has to do with what you do with steering wheel

Me being a slow poke driver I tend to hold the wheel into a turn just slight bit longer before I let the wheel release
Now if the car is setup to oversteer slightly I will tend to spin the car or just have all kinds of problems

my co-driver (a friends son 25 years old but a national level RC car driver) would tend to release the wheel just a little sooner let the car track out and would hardly ever have problems with my car oversteering

Now the result of holding the car in a turn just that little bit slows the car and you end up scratching your head why am I slow I am doing everything right

Anyway a few thought and observations

Davegt74

[ELO168]

I run 225/50/15 Ra1 on my Crx without any problems.
15x7 rota slipstreams
650# in front and 850 for rear.